Nuclear Reactor at Three Mile Island Eyed for 2027 Restart; Constellation Energy Aims to Supply Power To Data Centers

By Keiichi Nakane / Yomiuri Shimbun Correspondent

17:32 JST, July 17, 2025

WASHINGTON — A major U.S. electric power company intends to restart the Unit 1 reactor at the Three Mile Island nuclear power plant as early as in 2027, about a year before its initial timeline of 2028, The Yomiuri Shimbun has learned.

As reasons for accelerating the restart, Constellation Energy Corp. said that progress was being made in training operators and preparing the backup power supply system.

The Unit 1 reactor ceased operation in 2019, but Constellation Energy announced its plan in September 2024 to restart the reactor to supply power to data centers operated by Microsoft Corp. Data centers, which process information using AI, require a considerable amount of electric power.

Constellation Energy submitted a request to the Nuclear Regulatory Commission to rename the Unit 1 facility as the “Crane Clean Energy Center,” and it was approved by the commission in May.

TMI’s Unit 2 reactor, which sits near Unit 1, was the site of a severe nuclear accident in 1979 in which the reactor partially melted down. Constellation Energy is believed to be seeking to dispel the negative image from the accident.